Priti Patel is on childcare duty when I ring to catch up with her after her turbulent last few days. She and her husband have one son, Freddie, who is seven years old. “He’s pushing back on doing his homework,” she says, with the weary laugh that all parents who have, or once had, a seven year old son will recognise without a moment’s hesitation.

Freddie must take after his mother. For Patel has been pushing back, too, rather than rolling over. Of the six Cabinet Ministers who left Downing Street to cross the river for Vote Leave headquarters on Saturday, she was the most junior: strictly speaking, she only has the right to attend Cabinet – as a Minister of State she is not a full member.

It follows that she therefore had the most to lose by parting company with the Prime Minister over Britain’s EU membership. If Remain wins, her boss at Work and Pensions, Iain Duncan Smith, will surely leave Cabinet. The other four members of that Ministerial Leave team look nearer the exit than the entry door of their top-flight service in government.

Patel, on the other hand, is a recent arrival around that Cabinet table and has her career stretching before her. To stand out against David Cameron’s deal will not, I’m sure, lead to dismissal if Remain triumphs. But Prime Ministers don’t take to being crossed, and there are other ways to blight the fortunes of Ministers who hold out or dig in: non-promotion, sideways shuffles, that marking of the card that leads eventually to being quietly dropped.

When I put this point to her, the Work and Pensions Minister bridles slightly. I can’t see her stiffen, but can hear it down the line. “I don’t take decisions based on thinking about what might be best for my career – strange though that may sound to your readers ” she says. “I came into politics with beliefs that I want to further. To represent my constituents is a privelege. To serve in government is a privilege.”

I don’t know whether or not it sound strange to ConservativeHome readers that Patel’s has deep-rooted Eurosceptic convictions, but it shouldn’t. She did, after all, once leave the Tories for James Goldsmith’s Referendum Party, returning to it only later. And she is a former columnist for this site whose writings were shot through with criticism of Brussels.

“This referendum has been 41 long years in the making,” she says, ticking off the period precisely, “but at last people will get to have their say.” But for all her long-time view, she neither knocks David Cameron’s deal nor claims she made her decision to campaign for a Leave vote as soon as the leadership threw its weight behind a poll. The Prime Minister “did the very best he could under the circumstances”.

So when did she make up her mind? “Once the summit was in sight the direction of travel was clear – and it was evident that difficult decisions would have to be made.” Patel studied the draft deal closely, and says that what moved her was her head as well as her heart. “It was a rational, not an emotional decision, and I recognise the hard work put in by the Prime Minister, not to mention his dedication and tenacity.”

None the less, “my fundamental view is that Britain will be freer, fairer and better outside the EU, and I believe that leaving it can be a great catalyst for change in a positive way. We should have confidence in ourselves and our future.” She doesn’t believe that the Leave Campaign should have a single leader – “everyone will have a part to play” – but is clearly relishing the debate ahead.

The effect of politicians on the outcome can be overstated. It seems to me that Iain Dale was right to say in his column for this site last week that the biggest influence on people will be there friends and family. But a lesson from the AV referendum may lie in the contrast between the two campaigns. No to AV was top-heavy with senior Conservative and Labour politicians. Yes to AV saw itself as a peoples’ campaign. We all know the result.

But whatever your view, Patel clearly will and should be one of the most prominent political faces of the Leave campaign. A colleague of hers said to me recently: “My teenage son started talking about the referendum recently, and said to me: ‘Why are all the people involved so old?’ ” It is a telling point. Tebbit and Heseltine, Lawson and Clarke, Duncan Smith himself and Johnson (Alan, that is): the ranks of both camps are scarcely short of older men.

Patel is different for reasons too obvious to need spelling out, but her appeal won’t be grounded in calculations about her youth, her sex or her background as the child of refugees from Idi Amin’s Uganda. (Read Andrew Gimson’s interview with her here, in which she describes how her father set up as a newsagent and rose at four in the morning to work.) It will be founded in the beliefs that drive her.

During Margaret Thatcher’s successful challenge for the Tory leadership in 1975, the Daily Telegraph ran an editiorial with the headline: consider her courage. It’s far too early to tell if Patel can follow where Thatcher went, and no person is quite like another in any event. But that headline is worth filching. Patel has shown courage in swimming against the tide, and a resolution that was, I think, never in doubt.